Specific Aim 1. To test the hypothesis that the RV in human PAH exhibits lipid deposition, increased glycolysis and impaired fatty acid oxidation. The investigators will measure RV oxidative metabolism and glycolysis in PAH patients and controls using positron emission tomography 11C acetate and [18F]fluoro-deoxy-D-glucose imaging and measure myocardial lipid accumulation using magnetic resonance spectroscopy imaging.